I recently started playing with 3D printing, and I have to say the official filaments from Bambu Lab are a delight. Just pop in a spool, and the printer reads the embedded NFC chip, instantly loading the proper material settings. Zero fuss.
Even better, their filament catalog is impressively broad. As someone new to the scene, this variety felt like opening a drawer full of unexplored possibilities. Naturally, I did what any mildly obsessed person would do:
I bought one of everything. Every. Single. Spool.
That’s when I noticed something in the fine print – some of these filaments need to be dried before use. Moisture ruins prints, and apparently even freshly delivered filament isn’t immune.
So, I went hunting for a smart filament dryer. Something that could regulate temperature, handle different drying profiles, maybe log data or sync with my existing smart setup. Unsurprisingly, most of what I found was either too basic, too clunky, or way overpriced. And since I had a five-day holiday ahead of me, a small mountain of filament to dry, and a pile of spare parts… I decided to build my own.
The design came together quickly in my head. At its core, a filament dryer is just a temperature-controlled heating chamber. So, I started with a sealed plastic box. For the controller, I use my SONOFF TH Elite (THR316D), connected to a THS01 temperature and humidity sensor, which can be mounted inside the box. The TH Elite monitors internal conditions and turns power on or off depending on preset thresholds.
For heating, I wired the output of the TH Elite directly to a PTC heating element – a compact, self-regulating heater. When the temperature inside the box drops below target, the controller supplies power to the PTC. When the environment hits the desired range, it shuts the power off.
But then I realized a flaw in the plan: a sealed box with a heater just traps moisture—it doesn’t remove it. I needed airflow.
To fix this, I needed to add two ventilation holes to the sealed box, then control them using small 12V DC solenoid valves. These valves handle the airflow – opening to let moisture out and closing to seal the chamber.
The solenoids are powered by a 220V-to-12V AC/DC module, which is also wired through the TH Elite. This way, when the heater kicks on, the vents open automatically. When the system reaches target humidity or temperature and the heater powers down, the valves close, sealing the chamber again.
No separate logic. No extra relays. Just synchronized power flow – clean and reliable.
The parts are on their way—I’ve already ordered the PTC heater and solenoid valves online, and they should arrive tomorrow. Once they’re in, it’ll finally be time to test whether this design holds up.
I’ll be testing different PTC wattages to see which one can most effectively raise the temperature inside the sealed box – 70°C? 80°C? Maybe even 100°C? Each material might require a different profile.
I’ll also observe how well the ventilation setup performs – whether the humidity actually drops once the temperature starts to climb, and whether those small air vents are enough to keep the box from turning into a moisture trap.
There will probably be plenty of trial and error – but that’s part of the fun: dialing in the variables, watching the sensor data, and hopefully not setting anything on fire.
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